package main

func Sum(numbers []int) int {
	sum := 0
	for _, number := range numbers {
		sum += number
	}
	return sum
}

func SumAll(numbersToSum ...[]int) (sums []int) {
    for _, numbers := range numbersToSum {
        sums = append(sums, Sum(numbers))
    }

    return sums
}

func SumAllTails(numbersToSum ...[]int) []int {
    var sums []int
    for _, numbers := range numbersToSum {
		if len(numbers) == 0 {
			sums = append(sums, 0)
		} else {
			tail := numbers[1:]
			sums = append(sums, Sum(tail))			
		}

    }
    return sums
}